Assailants believed to be members of the Allied Democratic Forces (ADF) first targeted a group of villagers from North-Kivu province that had crossed into neighboring Ituri province to look for arable land near the Ituri River on Aug. 25.
Christophe Munyanderu, coordinator of the local group Convention for the Respect of Human Rights (CRDH), said ADF fighters had executed more than 40 men, women and children in five villages since Thursday.
"All this under the eyes of the authorities," said Munyanderu. "We are dying here but nothing is being done."
Mathe Mupanda Salomon, a nurse at a hospital in one of the villages, said he saw the bodies of 26 villagers who were killed and 76 kidnapped in one of attacks.
The head of the surrounding Babila-Bakaiko locality, Charles Kisubi Endukadi, confirmed rebels had attacked several villages and that most bodies had yet to be recovered.
The Congolese army did not immediately respond to a request for comment.
The ADF, a Uganda militia with ties to Islamic State, is one of several armed groups wrangling over resources and attacking civilians in Congo's east, which is rich in minerals such as tin, tantalum, tungsten and gold.
Escalating attacks prompted the government to declare a state of siege in Ituri and North Kivu in April 2021. But the security situation has continued to deteriorate under military rule, United Nations experts said in June.